The present invention relates to a battery capacity measuring and remaining capacity calculating system. More particularly, the present invention is concerned with a battery capacity measuring device for vehicle batteries, a remaining capacity calculating system for vehicle batteries, an automatic engine stopping/starting system for vehicles based on a remaining battery capacity, an electrical rotating machine control system for vehicles based on remaining battery capacity, and a fully-charged state judging system for vehicle batteries.
A battery mounted in a vehicle is used as a power supply that supplies power to a starter for an engine and other accessories. The battery is charged from time to time by means of a generator that operates with power exerted by an internal combustion engine. A battery capacity measuring device measures a current battery capacity, and the generator is controlled based on the detected battery capacity.
For example, Japanese Unexamined Patent Application Publication No. 6-351166 discloses a technology for maintaining a battery capacity, which matches power consumption required by a load, with low fuel consumption, and preventing deterioration of a battery caused by overcharging or over-discharging. Herein, when a battery is nearly fully charged, an adjusting voltage is lowered for fear the battery may be overcharged. Nevertheless, generation must be able to be achieved with low fuel consumption. In contrast, when the battery capacity is insufficient, the adjusting voltage is raised for fear the battery may be over-discharged. In this example, the battery capacity is calculated based on an integrated value of charging/discharge current values of the battery detected by a current sensor.
In case a battery capacity is calculated based on an integrated value of charging/discharge current values of the battery, the precision in detection performed by a current sensor has a significant meaning. In particular, if a detected current value contains an error that must be offset, the offset values are integrated in order to calculate a current battery capacity. This makes it hard to properly control charging of the battery. The offset error is detected by measuring a current that flows when a circuit is open. As far as a vehicle is concerned, even when an engine is stopped, power is fed to accessories including a clock. It is therefore hard to measure the current with the circuit fully open. A method has been proposed in efforts to cope with this problem, wherein a dark current flowing with the engine stopped is estimated in advance, and an offset error is calculated with the dark current removed.
However, the dark current flowing with the engine stopped varies depending on the use state of an accessory or the type thereof. The dark current flowing with the engine stopped cannot always be estimated correctly. Thus, there is a fear that an error in a detected charging/discharge current may get larger.
According to the first mode of the present invention, the present invention attempts to solve the above problem underlying related arts. An object of the present invention is to provide a battery capacity measuring device capable of measuring a battery capacity with high precision.
A remaining capacity calculating system for calculating a remaining capacity that represents the charged state of a vehicle battery is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 10-319100. In this example, while a vehicle is running, a current flowing through a battery is measured in order to predict a change in the local concentration of electrolytic solution. The degree of polarization caused by the change in the concentration is then estimated. A remaining battery capacity is calculated using a representation of a voltage-current characteristic measured when the effect of polarization is limited.
However, the conventional remaining capacity calculating system cannot estimate the degree of polarization during, for example, running of a vehicle during which a battery is continuously charged. This poses a problem in that the remaining capacity of the battery cannot be calculated precisely when it is needed.
According to the second mode of the present invention, the present invention attempts to solve the foregoing problem underlying related arts. An object of the present invention is to provide a remaining capacity calculating system for vehicle batteries, an automatic engine stopping/starting system, and an electrical rotating machine control system. Herein, polarization occurring in a battery and adversely affecting the charged state of the battery that is a secondary battery is utilized effectively.
Fully-charged state judging systems for vehicle batteries include a system that monitors a rise in the voltage at the terminals of a battery (for example, a lead-acid battery) to judge whether a battery is fully charged. This device utilizes a phenomenon that as long as a battery is charged with a constant current, when the battery is nearly fully charged, the voltage at the terminals of the battery rises.
However, when a vehicle is running, polarization attributable to a change in a charging/discharge current or a change in the concentration of electrolytic solution, occurs in a battery. Moreover, an output voltage of an alternator is regulated by a regulator and provided as an adjusting voltage. Therefore, a rise in the voltage at the terminals of the battery is not always associated with the fact that the battery is fully charged. This poses a problem in that even when the voltage at the terminals of a battery is monitored, it may not be able to judge highly precisely whether the battery is fully charged.
According to the third mode of the present invention, the present invention attempts to solve the above problem underlying related arts. An object of the present invention is to provide a fully-charged state judging system for vehicle batteries and a remaining battery capacity calculating system employing the fully-charged state judging system. The fully-charged state judging system can highly precisely judge whether a battery is fully charged, irrespective of an adjusting voltage produced by a regulator or polarization occurring in a battery.
In the aspect of the present invention set forth in claim 1, a microcomputer (80) includes a fully-charged state judging means.(80e), a detected current integrating means (80a), a dividing means (80b), and a correcting means (80c). The fully-charged state judging means detects whether a battery is fully charged. The detected current integrating means integrates the current values that are detected by a current sensor during a period from the instant a battery is fully charged to the instant it is fully charged thereafter. The dividing means divides an integrated value of detected current values provided by the detected current integrating means by, the length of the period. The correcting means corrects a detected current with an offset using a quotient provided by the dividing means.
Owing to the above features, when a battery is fully charged, a battery capacity that shall be denoted by SOC (state of charge) is restored to 100% that is identical to a battery capacity attained when the battery is fully charged previously. During a period from the instant a battery is fully charged previously to the instant it is fully charged this time, the battery is discharged and charged by the same amount of current. Therefore, an integrated value calculated by integrating the current values that are detected during the period from the instant a battery is fully charged previously to the instant it is fully charged this time contains offset values that are caused by the current sensor. The integrated value of the detected current values is divided by the length of the, period that is an integration period. Thus, the offset is calculated irrespective of a use form of a battery, that is, for what load such as an engine starter a battery is used. Consequently, an accurate charging/discharge current can be determined. Eventually, the battery capacity can be measured highly precisely.
Moreover, in the aspect of the present invention set forth in claim 2, a fully charging means (80d) is included so that, when a predetermined time has elapsed since the instant a battery is previously fully charged, the fully charging means will control a generator to fully charge the battery. Owing to this features when the predetermined time has elapsed, the battery is fully charged. Consequently, the offset error can be checked at substantially regular intervals. Furthermore, the battery capacity can be measured highly precisely.
Moreover, in the aspect of the present invention set forth in claim 3, the remaining capacity calculating, system for vehicle batteries includes a voltage detecting means (50) a current detecting means (40), an index calculating means (320), a control means (340 to 351, and 430 to 351), and a calculating means (361). The voltage detecting means (50) detects the voltage at the terminals of a battery (B) that is mounted in a vehicle having an electrical rotating machine (10, 10A) connected to an engine (E), and that is charged by the electrical rotating machine. The current detecting means (40) detects a current flowing through the battery. The index calculating means (320) calculates an index of polarization occurring in the battery according to the detected current. The control means controls the output voltage of the electrical rotating machine so that the index of polarization will remain within a predetermined range which permits limitation of the effect of polarization on the charged state of the battery. When the index of polarization remains within the predetermined range, the calculating means calculates the remaining capacity of the battery using the detected terminal voltage of the battery, that is, the open circuit voltage of the battery.
Owing to the above features, the control means controls the electrical rotating machine so that the index of polarization will remain within the predetermined range permitting limitation of the effect of the polarization on the charged state of the battery. At this time, the remaining capacity of the battery is calculated based on the detected terminal voltage of the battery, that is the open-circuit voltage of the battery. In short, the electrical rotating machine is actively controlled in order to cancel a change in the index of polarization so that the index will fall within the predetermined range. The remaining capacity SOC is calculated based on the open-circuit voltage at the terminals of the battery. Consequently, the calculation of the remaining capacity based on the open-circuit voltage of the battery can be performed timely and precisely, if necessary.
In the fourth aspect of the present invention set forth in claim 4, an automatic engine stopping/starting system for vehicles includes the remaining battery capacity calculating system set forth in claim 3, and an inhibiting means (230) that inhibits automatic stoppage of an engine when the remaining battery capacity falls below a permissible value.
Owing to the above features, automatic stoppage of an engine is inhibited based on a remaining capacity calculated by the remaining capacity calculating system. Consequently, automatic stoppage of the engine can be inhibited precisely. Thereafter, when an automobile is started, engine stall can be reliably prevented.
Moreover, in the aspect of the present invention set forth in claim 5, an electrical rotating machine control system for vehicles includes the remaining capacity calculating system for vehicle batteries set forth in claim 3, and a control means (431). Assuming that the electrical rotating machine is a motor-generator (MG), the control means controls the motor-generator so that the motor-generator will assist the engine when the remaining capacity is equal to or larger than a permissible value.
Owing to the above features, the control means can precisely control the electrical rotating machine according to the remaining capacity calculated by the remaining capacity calculating system so that the electrical rotating machine will assist the engine. Consequently, the battery satisfactorily maintains the property of receiving a charging current. Eventually, the battery can be charged timely and efficiently. This results in efficient collection of energy.
Moreover, in the aspect of the present invention set forth in claim 6, an electrical rotating machine control system for vehicles includes a voltage detecting means (50), a current detecting means (40), an index calculating means (320), and control means (340 to 351 or 430 to 451). The voltage-detecting means detects the voltage at the terminals of a battery (B) that is mounted in a vehicle having an electrical rotating machine (10 or 10A) connected to an engine E and that is charged by of the electrical rotating machine. The current detecting means detects a current flowing through the battery. The index calculating means calculates an index of polarization in the battery according to the detected current. The control means controls the electrical rotating machine so that the index of polarization will remain within a predetermined range permitting limitation of the effect of polarization on the charged state of the battery.
Owing to the above features, when the index of polarization remains within the predetermined range, the control means precisely controls the electrical rotating machine so that the electrical rotating machine will assist the engine. Consequently, the battery can maintain its property of receiving a charging current. The battery can be charged timely and efficiently. This, results in efficient collection of energy.
Moreover, in the aspect of the present invention set forth in claim 7, a fully-charged state judging system for vehicle batteries includes a voltage detecting means (50), a current detecting means (40), and a fully-charged state judging means (610, 620, 630, and 1030). The voltage detecting means detects the voltage at the terminals of a battery (B) that is mounted in a vehicle having an alternator (10) and a regulator (30) for regulating the output voltage of the alternator, and that is charged with the output voltage of the alternator (10) regulated by the regulator (30). The current detecting means detects a current flowing through the battery. When the detected terminal voltage and the detected current belong to a predetermined fully-charged state judgment domain, the fully-charged state judging means judges that the battery is fully charged. A fully-charged state judging system further includes an index calculating means (810, 1003) for calculating index of polarization in the battery according to the detected current belong to a predetermined fully-charged state judgment domain, the fully-charged state judging means judges that the battery is fully charged.
Owing to the above features, the fully-charged state judging means judges whether the battery is fully charged by checking if the index of polarization falls within a predetermined range of index values when the detected terminal voltage and the detected current are in the predetermined fully-charged state judgment range, it is judged that the battery is fully charged. The fully-charged state of the battery can be precisely judged compared with it is judged based on the voltage at the terminals of the battery.
In the aspect of the present invention set forth in claim 8, the predetermined fully-charged state judgment range employed in the fully-charged state judging system for vehicle batteries set forth in claim 7 is a range specified with voltage values higher than the rated voltage of the battery with the battery charged 90% or more and with current values assumed by a zero current flowing through the battery or a discharge current of the battery. Consequently, the advantage of the aspect of the present invention set forth in claim 7 can be attained more reliably.
In the aspect of the present invention set forth in claim 10, the predetermined range of index values set in the fully-charged state judging system for vehicle batteries set forth in claim 8 is a range of index values permitting negligence of a change in the concentration of electrolytic solution in the battery. Owing of the feature, the advantage of the aspect of the present invention set forth in claim 8 can be attained more reliably.
In the aspect of the present invention set forth in claim 11, a fully-charged state judging system for vehicle batteries includes a voltage detecting means (50), a current detecting means (40), an index 10 calculating means. (710 and 1003), and a fully-charged state judging means (720, 730, 740, and 1030). The voltage detecting means detects the voltage at the terminals of a battery (B) that is mounted in a vehicle having an alternator (10) and a regulator (30) for regulating the output voltage of the alternator, and that is charged with the output voltage of the alternator regulated by the regulator. The current detecting means (40), detects a current flowing through the battery. The index calculating means calculates an index of polarization caused by the electrolytic solution in the battery. When the detected terminal voltage belongs to a predetermined fully-charged state judgment range and the index of polarization falls within a predetermined range of index values, the fully-charged state judging means judges that the battery is fully charged.
Owing to the above features, when the detected terminal voltage belongs to the predetermined fully-charged state judgment range and the index of polarization falls within the predetermined range of index values, the battery is judged to be fully charged. Consequently, the fully-charged state of the battery can be highly precisely judged compared with when it is judged based on the voltage at the terminals of the battery.
In the aspect of the present invention set forth in claim 12, the predetermined fully-charged state judgment range set in the fully-charged state judging system for vehicle batteries set forth in claim 11 is a range specified with voltage values higher than the rated voltage for the battery with the battery charged 90% or more. The predetermined range of index values is a range of index values permitting negligence of a change in the concentration of electrolytic solution in the battery. Owing to the feature, the advantage of the aspect of the invention set forth in claim 11 can be attained more reliably.
In the aspect of the present invention set forth in claim 13, the fully-charged state judging system for vehicle batteries set forth in any of claim 7, claim 8, or claims 10 to 12 includes a regulator control means (971 to 982). The regulator control means controls the regulator repeatedly at regular intervals so that an adjusting voltage to be produced by the regulator will be set to a predetermined value higher than a normal adjusting voltage value. The fully-charged state judging means make the judgment when the adjusting voltage to be produced by the regulator is set to the predetermined value.
Owing to the above feature, when the adjusting voltage to be produced by the regulator is set to the normal adjusting voltage value, the advantage of the aspect of the present invention can be provided, while the judgment on whether the battery is fully-charged will not be adversely affected.
In the aspect of the present invention set forth in claim 14, the remaining capacity calculating system for vehicle batteries includes a fully-charged state judging system for A vehicle batteries set forth in any of claim 7, claim 8, or claims 10 to 13 and a remaining capacity calculating means (520). The remaining capacity calculating means calculates the remaining capacity of the battery when the fully-charged state judging system judges that the as battery is fully-charged. Owing to these features, the remaining capacity of the battery can be calculated highly precisely.
In the aspect of the present invention set forth in claim 15, the remaining capacity calculating system for vehicle batteries includes the fully-charged state judging system for vehicle batteries set forth in claim 8 or 11, an index judging means (1010), a learning means (1051), and a remaining capacity calculating means (1053). After the fully-charged state judging means included in the fully-charged state judging system judges that the battery is fully charged, the index judging means judges whether the index of polarization falls within a range of index values permitting stabilization of the open-circuit voltage of a battery. When the index judging means judges that the index of polarization falls within the range of index values permitting stabilization of the open-circuit voltage of a battery, the learning means learns the relationship between the remaining capacity and the open-circuit voltage established based on the degree of deterioration of the battery. The remaining capacity calculating means calculates the remaining capacity of the battery by referencing the result of learning performed by the learning means using the open-circuit voltage of battery.
Owing to the above features, the open-circuit voltage of the battery is used to calculate the remaining capacity. The remaining capacity can therefore be calculated quickly. Moreover, after the fully-charged state judging means included in the fully-charged state judging system judges that the battery is fully-charged, when it is judged that the index of polarization falls within the range of index vales permitting stabilization of the open-circuit voltage of the battery, the relationship between the remaining capacity and open-circuit voltage established based on the degree of deterioration of the battery is learned. The remaining capacity is calculated by referencing the result of the learning using the open-circuit voltage of the battery. Consequently, the remaining capacity can be calculated highly precisely, irrespective of the deterioration of the battery.
In the aspect of the present invention set forth in claim 15, the learning means included in the remaining capacity calculating system for vehicle batteries set forth in claim 15 learns the relationship between the remaining capacity and open-circuit voltage by referencing the relationship between the remaining capacity and open-circuit voltage established in the initial stage of the battery after it is judged that the battery is fully charged. At this time, the learning means takes account of an amount of discharge current of the battery released until the index judging means judges that the index of polarization falls within the range of index values permitting stabilization of the open-circuit voltage of the battery after it is judged that the battery is fully charged. Owing to this feature, the advantage of the aspect of the present invention set forth in claim 15 can be further improved.
Incidentally, the numerals in parentheses denote a exemplary means that will be described in relation to embodiments later and that realize the aforesaid features.